1. Field of the Invention
The present invention generally relates to a wiring board, and particularly relates to a method of manufacturing a wiring board having a decoupling capacitor which is connected to a semiconductor chip.
2. Description of the Related Art
In recent years, with a semiconductor device such as a semiconductor chip becoming smaller and thinner, there has been a need to make a decoupling capacitor (which may also be called a bypass capacitor) smaller for suppressing changes in the power supply voltage of the semiconductor chip so as to stabilize its operation, and to use thin-film technologies for the decoupling capacitor.
Moreover, as the operating frequency of the semiconductor chip is expected to become higher in order to further increase the operating speed of the semiconductor chip in the future, the decoupling capacitor is preferably installed in the vicinity of the semiconductor chip in order to reduce the inductance of the decoupling capacitor connection.
Thus, different decoupling capacitors and methods of installing the decoupling capacitors that respond to the need as described above are being proposed.
For example, when a semiconductor chip is mounted on a wiring board so as to use the semiconductor chip, a method of mounting a decoupling capacitor on the back side of a wiring board, or in other words, on the side opposite the side on which the semiconductor chip is mounted (for example, refer to Patent Document 1), and structures and forms for embedding the decoupling capacitor into the wiring board are being proposed (for example, refer to Patent Documents 2 through 4).
Patent Document 1
JP2003-264253A
Patent Document 2
JP2004-14573A
Patent Document 3
JP2004-152883A
Patent Document 4
JP2004-281830A
However, for installing a decoupling capacitor in a wiring board on which a semiconductor chip is mounted, a problem could arise with the reliability of the wiring structure to which the decoupling capacitor and the semiconductor chip are connected.
For example, when trying to simply configure the wiring structure to which a decoupling capacitor and a semiconductor are connected, it is preferable that via wiring be formed such that it pierces the decoupling capacitor, thereby simplifying the wiring structure and making it possible to reduce the impedance of the wiring structure.
However, as the via wiring and pattern wiring connected to the via wiring are minituarized, problems could arise with the registration tolerance (the alignment tolerance) of the via wiring, or with the reliability of the connection between the via wiring and electrode layers of the decoupling capacitor, or with the reliability of the connection between the via wiring and the pattern wiring, possibly making it difficult to make a low-impedance structure which is superior in the reliability of the connection.